Parabolic flight, to provide a half minute of weightlessness in conventional subsonic transports, has been performed by NASA for over forty years, and this has been viewed for a long time as one of the prime areas to privatize. In the past, the political opposition to this from NASA, and some of its supporters on the Hill, has been intense. However, it raises a legitimate question: if we can’t privatize simply flying a Boeing transport, how can we even think about privatizing the Space Shuttle or International Space Station, as many seem to want to do?
In addition to the political resistance, another problem with private parabolic aircraft is that there is no clean regulatory category for them within the FAA. Under current law, if an air transport service is offered to the public, the operator must operate under the rules of Part 121 or 135 (depending on the size of the aircraft) and the aircraft must be certified to operate under that regime. While commercial transports are certified for Part 121, they are not certified to perform the parabolic maneuver necessary to provide the weightless experience. Thus, to operate one under Part 121 for weightless maneuvers, it must be modified as necessary for the maneuver, and receive a Special Type Certification (STC) for those maneuvers from the FAA engineering division and AVR. This is a process that could prove to be both time consuming and very expensive (though hopefully not as expensive as the original certification process, which can involve hundreds of millions of dollars).
It should be noted that NASA itself does not meet these requirements with their military KC-135 cargo aircraft, but used one, despite this, to provide commercial parabolic services to Imagine Entertainment for the filming of the movie Apollo XIII. Since then, while they can continue to do these maneuvers for their own astronaut training and research, they have been barred by the FAA from further commercial work (resulting, for example, in actor/producer Bruce Willis being turned down when he requested the use of a NASA KC-135 for the filming of Armageddon).
Another ironic policy anomaly resulting from NASA's unwillingness to privatize parabolic flight is that, even though they are not and cannot be certified by the FAA to carry paying passengers, they regularly carry college, and even high-school students in their aircraft to perform student experiments.
A result of NASA's continued operation of their own aircraft for astronaut training and weightless research is that the market for private aircraft is significantly reduced. Like the launch problem, costs are potentially high for a parabolic aircraft business because there may not be enough customers to fully utilize the aircraft, and amortize the high costs of getting the special type certification necessary. If the private entity could pick up some or all of the NASA business as a contractor, in addition to the private market demand for research and weightless experiences, it might make such a venture more economically viable.
As a result of this, to the author's knowledge, other than past attempts by Interglobal Space Lines, and the now-failed Casey Aerospace corporation, there is only one private entity (the Zero-G company) seriously attempting to get a transport aircraft certifed for commercial parabolic flight in the U.S., and their progress in doing so remains uncertain. However, if they do get the aircraft certified for Part 121, it is estimated that the cost per person per one hour flight would be on the order of a minimum of several hundred dollars, and could range to an order of magnitude more, depending on the demand level. How large the market would be at these prices is unknown.
Incredible Adventures has been selling such a service on the Russian IL-76 cosmonaut training aircraft for several years for about five thousand dollars, not including travel expenses to, from and within Russia. At that price, they have only sold a dozen or so experiences per year (one or two flights). It is not clear to what degree the market size for this is depressed by the necessity to travel to Russia. The kinds of individuals who can afford this kind of experience don't generally have the time to devote to such a relatively long trip, and given the current crime levels and corruption there, many consider it highly risky, in addition to the inconvenience. On this basis, and feedback from the customers, it is estimated that a similarly-priced U.S. domestic experience would generate demand at least one, and possibly two orders of magnitude greater than the Russian equivalent.
In the absence of such a commercially-certified aircraft, there are only two domestic options for providing parabolic experiences—flights in aircraft certificated for experimental flight operations (as has been done in the past by Weaver Aerospace Corporation) or a change in NASA (and FAA) policy to allow paying passengers on the KC-135. The former is very expensive, and occurs quite rarely. The latter option would establish a precedent for use of the Shuttle in a similar manner, but would meet strong resistance from some within both NASA and the FAA. This would not eliminate the issue of aircraft certification, and it isn't clear whether it could be done simply as a matter of agency policy, or if legislation would be required to implement it.
The best solution would be to have NASA actually contract out for their parabolic services on a private commercial aircraft. In addition to bringing the activity under the regulatory umbrella, this could aid the fledgling space tourism business in at least three ways:
First, it would establish precedents for privatizing NASA activities in general, perhaps breaking down some of resistance within the NASA bureaucracy to Space Shuttle and ISS privatization that clearly exists, despite public statements and official policy to the contrary.
Second, it would bring economies of scale to the business by consolidating the private and government markets, thus reducing costs to both NASA and the customers among the general public.
Finally, it would open up weightless experiences to the general public. At costs of a few hundred dollars per flight, thousands would experience it, providing a valuable data base on how to handle the issues of motion sickness, and introducing the public (many of whom might be potential investors) to the concept of private space tourism activities. This could provide a foundation for a public space travel and tourism market that could be built on further with the higher and faster experiences discussed in the next sections.